When should I message this girl back?

I recently got back in touch with a girl I knew/ was talking to years ago. She said she was going on holidays and would be back on the 20th so I messaged her asking about her holidays on the 20th she replied like a day later so I did the same but have had no response. Do I wait a day or two or just leave it? Surly she's keen or would not have responded? I'm a little out of touch as have only recently got divorced